Deyices for following a movable object



Dec. 11, 1956 T. TElLING DEVICES FOR FOLLOWING A MOVABLE OBJECT 3 Sheets-Sheet 1 Filed Sept. 25. 1951 ,Q R x m8 Y Dec. 11, 1956 T. TElLiNG DEVICES FOR FOLLOWING A MOVABLE OBJECT 3 Sheets-Sheet 2 Filed Sept 25, 1951 Dec. 11, 1956 'r. TElLlNG DEVICES FOR FOLLOWING A MOVABLE OBJECT Filed Sept; 25, 1951 3 Sheets-Sheet 3 mwookmovi 3Q 25% 8954+ b 26 5:

nited States DEVICES 'FOR :EOLLOWIN G 'A MOYABLE OBJECT Claims... (Cl. 235-615) Thewpresenti invention relates to devices for following .amobject-J during itsimotion so asv tosdetermine; the geometrical coordinates ofthe object. More. particularly,

.thepinvent-ion relates to a device ofthat kind in whichone or several tracking-members, for example directional instruments or range-finders, adapted-anally instant-to indicate by thein. adjustments -the .polar coordinates ofzthe object. inna -twoor. three-dimensional: coordinate system, obtainuthcirsmovement from automatically acting operat- 1ingwmembers; the movements of which: during the course I ofrtracking; is initiated. and corrected by manually or an- 1 tomaticallyz-,operable controlzmembers.

zsuchedevices'iare:mainly :used fonfollowingemovements of targets, for example when laying guns, wherefore-the description of i'the-rinventionrwill hereinafter :relate to a device-especially adapted:for-,that =-purpose.But-the inv vent-ion is,- of course, notrestricted thereto.

--Myinvention-,uwill. be;.rnore clearly understood: from ..-ther.*specification. hereinafter. following by-reference to the accompanying drawings; in which:

Fig. 1 is. a-vector.;diagram:;explaining.the-principles I of my invention;

F i g.. 5.2 schematically illustrates a :the, :manner of .;trans- .mittinginput-signals'ior .controllingccomponents ofispeed in 11116? rectangular; :coordinate system: according to my I invention; I

l- Fig.13-:shows-;the;:manner of :coordinating :the sighting and ztrackingrzcomponentsof :myrinvention; rand Fig.c :4 "diagrammatically showsi-the:manneraof trans- :"mitting polar coordinate :input: signals: .ini-thev. systenr of my invention.

.1Theproblemlunderaconsideration .w'ill .belpresented and thejtditficulties zwhen solving-.vsame will be: indicatediwith .reference to El g. lot the annexed drawings.

:cIn-z Fig.1 lzian object assumed-tonmovecalong: the; dash line' M1+-M2 :is; designated'by: M. z: For rexamplmnwhen laying a :;gun;.-; the? range,1 the: ialtitudinal' :angle; and;- the azimuth .angle;1:that 'is xradiusevector. LAv asawellz. as the angles e pand-flfi in theqfigure rare; measured:.continually. The mode of performing the tracking movementubeing nearest: atlhanduconsists inzdirectly. actuatingxthe: trackingamember: ionnnembers," which. in an (optical sight consist of: directional .Jand: range r..firrdingndnstruments,"by means of their:operatingzhandcwheels or-lthezlikeathus having to .beekeptxmoving::continuously. 2; This. method =is,:-' however; relatively; imperfect. ibecause z the '1 tracking I movement; will in; this:case be :efiectedprincipally. by :correction pointafter point. in :the path oftmovementzot the object, .viz. byithezadjustment of the directional and range finding::instruments,r.causing;moreron less regulanizcontinuousxoscillations of themeasured :point aboutttheitarget. Thus,xthe 'speedzot :thetarget. intherzrespective coordinate. of. the polar. coordinateisystemiis. in. this case I represented by: the :rotary. ;velocity' of .'.the; corresponding operating hand-wheel.

.The movement of, a target. isas a rulenniformand-rectilinear; '1Thus,;if' the. assumption is'made. thattthesatarget "Mcmoves' in a:straightlline-course at aconstaLnt-speedt.

along the line M1"-M2 ibwill-beeasily understood that the time derivatives=of 'A,"y and ,8 are not constant, that is, the components of velocity in the polar coordinate .--system -varyiduringpthe course of tracking. 2 This involves,

in turn, that the average rotary speed of the operating hand xwheels has toberchanged successively use that a subjective estimation offthe rotary velocity. as required tomaintaincoincidence between the-point of aimwand theiobject'wwithathe-aid of previous observations: will be It is;.betten to:-useseparateuoperating means;-- which controlzthet-'tracking-member or members mechanically to perform; automatically. a movement which. is established by "observation of f theprevious movement of ;the. object, ViZ;.'OI1 the assumption'sthatsa'id movementwill' :thereafte'rfollow a law ofmot-ion established-byxthe' observations;- Thus, after thisaautomatical movement has beenzinitiated,;:only;.required :corrections of same :need

. towbezmade'z duringrthecourse of tracking, viz. 1accord ing 38.11161POiHi10f'13iI1'1 proves nottocoincide 'withlthe: 1 target dependingiz-ron inaccurate. measurement of the: movement of rthextarget' or: inconsistencies of the. move- ..ment of; the {targetwithrther law of movement as pre-- :sumed.

etiecti-ng'xthe tracking: movement, quantities: are, accord- :ing to therinventiomt-produced that: represent such con-- stant components ofvelocityeiwhich, after'integration and :-transformation.. of:: coordinates,zi.actuate the adjusting a means ;of-;:the rtracking member .or. members.

Since the .:observations of the movement-of the target are made in :the rpolar. coordinatesceach'. input' signal for setting the 7. automatical:trackingvmovement has to primarily repre- ..sent-icomponents=.of speed-inthi's system of coordinates. :From the.following-description. of Fig. 2 it will be apparent:- :how::sa'id input signals aretransmitted and caused to: influence-xtheisconrponentsr :of 1 speed. in. the rectangular .TCOOI'dlIIatCT system: in .a desired manner, said figure show- :sing:tveryr-diagrammatically I an .example of a practicable ."GfllbOdiHlEl'liZi-Of'f'fil'l' zarrangementaccording. to the in- 'vention.

Refermngzto FigrZ of: theidrawings, 1, 2 and 3. desig- .:natee:bal1- andldiscdntegratorsxknown per se, each havingswdiseila, 2a, 3a which are: :each. driven at a constant .rotaryizvelo'city'=by a-rnotor.and-:have each a ball 1b, 2b,

.Sbu(in;practiceiconveniently.twou balls engaging each sother ineeacht.aintegrator). Said: ballsitransmit the motiorL-ofxthet discszla; 2a,.- 3afto a roller 10,. 2c and 3c the time integral ofthe motion of the screws.

respectively, and :thetrradial distance of said balls from the: center Oflthfi' disc .can' be adjusted .by means of a screw 1d,;.:2d, 3d. By. this arrangement the angle of rotation of the-rollers 1c,- 2c; So will be proportional to The -angularpositions of said screws represent, according to "the invention, components of speed in said rectangular rand-z. Thusy theintegrators .1, 2 and 3 produce instantaneous values of thecoordinates x, y, and z of the. target:

system of coordinates "which'are designated by x, y

' Patented Dec. 1 1, 1956 v As shown in Fig. 1 the following relations exist between the coordinates x, y, z on one hand and A, 'y, e on the other hand:

x=A cos 7 cos y=A cos 'y sin ,6 Z=A sin 'y The projection of radius vector A on the xy-plane is =A cos 'y.

The angles of rotation of the rollers and 2c of the integrators 1 and 2 are proportional to the x and y coordinates and introduced into a secondary calculator or coordinate transformer 4, of the kind shown in United States Patent No. 2,340,865 to Chafee, which calculates corresponding values of ,3 and A cos 'y from the values of x and y and adjusts the shafts 5 and 6 so that the angles of rotation of the latter will be proportional to said values. The shaft 5 operates a sight 37 for adjustment in azimuth and the shaft 6 is connected to another secondary calculator or coordinate transformer 7, of the kind shown in Figure 3 of United States Patent No. 2,340,865 to Chafee, Whichat its input side is also connected to the roller 3c of the integrator 3 so that it receives an angle of rotation therefrom that is proportional to the z coordinate. The calculator 7 calculates from the components z and A cos 'y the coordinates 'y and A in the polar system of coordinates and transmits them as angles of rotation of the output shafts 8 and 9 to the sights 36 and 35 for adjustment for the 'altitudinal angle and the range.

The shafts 5, 8 and 9 are in conventional manner connected to a range and position instrument having the directional sights 36, 37 and the range sights 35 and to a Selsyn transmission system 38, 39, 40 or the like for introducing the data A, 'y, ,B to a gun fire control instrument 41, or for transmission of the tracking motion to a Searchlight battery or another device. They can, of course, also be provided with graduations for visual reading.

From the foregoing it is apparent that each tracking motion as having been set, corresponds to constant angular settings of the input shafts 1d, 2d and 3d of the integrators 1, 2 and 3. Thus, at each tracking, constant angular settings are primarily to be made which correspond to the motion of the target and which are thereafter adjusted 1 according as corrections prove to be required.

Initiation and correction of the tracking movement is effected by means of error correcting members consisting of the control or input handles 10, 11 and 12. (Figs. 2 and 4 of the drawings) to produce operating quantities A1, 7 and 8 responsive to the range A, the altitudinal angle 7 and the azimuth angle 9. Thus, the handles 10, 11 and 12 operate tachometer generators 13, 14 and 15 (Figs..2 and 4) the windings 34 of which are connected to the network (not shown) so that said generators produce output voltages A1, and 5 (Fig. 4) proportional to the time derivatives of the rotary movements of the handles 10, 11 and 12. Said output voltages, proportional to time derivatives of polar components, are converted into rectangular coordinates in resolvers 16 and 17 constituting primary coordinate transformers. Thus, the voltage A1 is introduced into. one of the primary windings of the resolver. 16 controlled by the shaft 8, the angular position of which is equal to the angle The other primary winding of the resolver 16 is supplied with the voltage A. obtained from A as described hereinafter in connection with the potentiometer 30 and from after voltage division in the potentiometer 30. Thereby voltages are produced in the secondary windings of the resolver 16, viz. the voltages A1'-sin +A- '-cos 'y and A1 cos 'y--A-'y '-sin 'y as indicated in Fig. 4. The voltages A1'-sin 'Y+A"y "COS 'y and A1'-cos 'yA"y '-sin 7 correspond to the vector projection of the original voltages normal to the horizontal plane and transmitted through the line 86 supplied to the motor 20 connected to the screw 3d of the integrator 3, viz. through an amplifier 23. The voltage Ai'-cos 'y-A-'y '-sin 7 corresponds to the projection of the original voltages in the horizontal plane, i. e. the xy-plane in the same direction as the vector A-cos 'y in Fig. 1, and is supplied to one of the primary windings of the resolver 17, which is controlled by the shaft 5 the angular position of which is equal to the angle 3. The other primary winding of the resolver 17 is supplied with the value A'cos 3, which is proportional to A -cos '7 supplied from shaft 6 in a manner described hereinafter in connection with the potentiometer 31 and to 3 obtained by voltage division in the potentiometer 31. Thereby the values transmitted through line 84 are induced in the secondary windings of the resolver 17 and transmitted through the lines 85 and 84, respectively, to the motor 19 connected to the screw 2d of the integrator 2, viz. through the amplifier 22, and to the motor 18 connected to the screw 1d of the integrator 1 through amplifier 21.

The potentiometer 30 is rotated by the shaft 9, the totation of which is proportional to A so that, if the input voltage of the potentiometer is constant, the output voltage of said potentiometer is directly proportional to A. Since the potentiometer 30 is, according to Fig. 4, from the tachometer generator 14 supplied with a voltage which corresponds to as explained hereinbefore-it will be obvious that the output voltage from 30 will be proportional to A '1 Similarly, the potentiometer is rotated by the shaft 5 the rotation of which corresponds to A-cos 'y,-and it is supplied with a voltage corresponding to 6 The output voltage of the potentiometer will then be proportional to A-cos 3 The motors 18, 19 and 20 are adapted to rotate at a velocity proportional to the voltage and, consequently, they act as integrators, the angles of rotation of which represent the time integrals of the rectangular components of the input voltages. In order that these motors satisfy as accurately as possible the condition as made, viz. that they rotate at a velocity proportional to the voltage, they are connected to tachometer generators 24, 25 and 26 the voltages of which are compared with the input voltages. The difference voltages are added to the input voltages whereby the motors obtain an excess voltage which counteracts tendencies of deviation from the law of constant proportions.

The initiation of a tracking movement is effected in such manner that the input handles 10, 11 and 12 are rotated so that the sights 35, 36 and 37 will train the target. After having attained this result the handles are arrested whereafter the sights continue training a movement in an invariable direction and at a constant speed through space, said data being determined by the angular positions of the shafts 1d, 2d and 3d of the integrators 1, 2 and 3 thereby having been set.

A more detailed explanation of the mode of operation of the device in connection with the transformation of coordinates from the voltages emitted by the tachometer generators 13, 14 and 15 might be justified.

As understood from the foregoing the momentary values (if alternating current, the momentaiy effective or instantaneous values)-of the components 01 the control voltages as transmitted from the resolvers 16 and 17 through the lines 84, 85, and 86 will represent accelerations in the direction of the respective x, y and z axes. Since the observations of the true position of the targetrel-ative to the measured point are made in the polar coordinate system the momentary values of the control voltages entering through the lines 27, 28 and 29 represent conveniently accelerations in range, elevation and azimuth. .Thus, the momentary variations of components that can be produced by the input handles 10, 11 and 12 consist of one component in the direction of the adjusted inclined range (controlled by the handle another component perpendicular thereto in the vertical plane (controlled bylthehandle 11) and a third component (cont-rolled by the handle 12) perpendicular to both the other components and in the horizontal plane. A simple analysis of. the relationship between the components in this polar coordinate system and the components in the rectangular coordinate system shows that a component in the direction of theline of sight will give an x-component proportional to cos 7200s )3, a y component proportional to cos 'y sin [3, and a 1 component proportional to sin 'y. A component in azimuth will give an x. component proportional 'toxsinifi .and a y component proportional to cos 13 but there is no z componentin this case. p p v I Since the control "ofth'e tracking movement in the device according to'the'inventionis characterized by correction to zero the relationship between'the movements (or positions) 'ofthe'inputhandles 10, Hand 12 and the control voltages "transmitted 'through'the lines 27 to 29 will be immaterial. The only -:condition for carrying the desired uniform tracking movement into efiect consists in that said control -voltages shall be reduced to zero after each correction so that the shafts 1d, 2d and 3d will be at rest thereafter and set the ball and disc integrators 1, 2 and 3 for constant components of rate x, y and 2'. Thus, in the embodiment as described in which the control voltages are gene-rated by tachometer generators 13, 14 and 15 operated by the input handles 10, 11 and 12 the desired tracking movement has been established as soon as the input handles have been arrested. It will be understood, however, that it is particularly convenient to primarily estimate the requisite rotary movements of the input handles approximately for correction of a deviation of the tracking movement from the movement of the target as observed in the sights 35, 36 and 37. Therefore, in the best constructions, as in the device described herewith, there is a direct proportionality between the rota tions of the input handles 10, 11 and 12 and the voltages generated thereby.

It should be noted that an observed inconsistency in elevation or azimuth between the point of aim and the target is perceived by the observer as a distance, which does not form any definite measure of the inconsistency, because the ratio between the measured distance and the actual one is proportional to the range. Therefore, if no special measures are taken, the distance thus having been observed does not give a full indication as to the manual adjusting operation that might be required to obtain a correction. For that reason potentiometers 30 and 31 are, according to the invention, introduced into the lines 28 and 29 for correction in the vertical and azimuth, respectively. The potentiometer 30 is operated from the shaft 9 (Figs. 2 and 3), and consequently, it is adjusted into an angular position that is proportional to the inclined range A of the point of aim. The voltage supplied through line 28 to the resolver 16 will in this manner be proportional to A. The following relationship between said voltage, Vi, the control voltage E, the range A, and the rotary velocity 21 of the input handle 11 will be valid:

Since the shaft 1d has a rotary velocity that is proportional to the input voltage Vi, as described hereinbefore, the displacement of the ball 1b of the integrator 1 will be proportional to Tf Vxdt. Since fVxdt is proportional to the projection of Vi on the x-axis, the displacement of the ball 1b will be proportional to Tf A-n'y-sin 'y-cos dz, i. e. proportional to the angle of rotation of the input handle 10.

The potentiometer 31 controls the azimuth angle exactly in the same manner. This potentiometer can be operated either by the shaft 6, as shown in Fig. 2 or from shaft 9, as shown in Fig. 3. If operated from shaft 9 a sensitivity is obtained that is dependent on the inclined range A and if operated by shaft 6 the sensitivity will be dependent on the-projectionA-cos y ofpsaid :range. on the xyaplane;

manner be dependent on the range wherefore it "mightcbe' suitable :in such cases tointroduce .into'the line 27 still another potentiometer 32 (Fig. 3) controlled by the.

shaft'9.

In the embodiment :as described hereinbefore the control voltages are proportional to the rotary veloci-ties'of the input handles 10, .11, and Y12. This is as :a rule especially convenient. Thus, a lead of the target is .to be regained it is sufli-cient to turn the input handles, esgl, through additional angles and .an accurate'coincidence can easilyfbe obtained by successively decreasing the rotary velocity of the said handles at the end of the correctionmovementand when "said movement. has been finished proper velocity-values have :been applied to the integrators 1,' 2 and 3. It is, however, also possible to'm-ake use of otherpr'inciples for generating control voltages, for ex:

ample so that :said voltages will be proportional to the angles of rotation of the input handles, which will occur, for example, if said handles are connected to potentiometers. Such an arrangement is, however, less suitable because the input handles have in such case to return to zero position at every correction and obtain dimension of acceleration.

The elements shown in the arrangement as described, such as integrators, ditferentiators, calculators, etc. can, of course, be replaced by other devices having equivalent mechanical or electrical functions.

The control members for initiating and correcting the tracking movement need not to be actuated manually. It is, for example, possible to utilize the device for tracking polar coordinates already measured (for example, by the aid of radar), whereby error measuring members are devised which compare the output coordinates of a radar equipment with the values A, 'y, 8 of the shafts 9, 8 and 5 and effect operation of the tachometer generators 13 to 15, or supply the resc-lvers 16 and 17 with input voltages directly through a diflerentiating device.

Since many changes could be made in the above construction and many apparently Widely different embodiments of this invention could be made Without departing from the scope thereof, it is intended that all matter contained in the above description as shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. Thus, in a simplified embodiment the device can, for example, also be used for training movements in one plane only, for example, the horizontal plane, and it is immaterial what kind of tracking members will be used since they might be chosen with respect to the purpose only for which the device is adapted. It is believed that the modifications as required for the equipment of the device with electro-optical or acoustic tracking members will be obvious to any, person skilled in the art.

I claim:

1. In a device for tracking a movable target, in combination, a plurality of sighting means adapted to continually follow the target and indicate the polar coordinates of said target, automatically operative speed integrators, error correcting members for producing correcting quantities, primary and secondary coordinate transformers, and automatically adjustable devices, said speed integrators being operable by said error correcting members and adapted to integrate components of speed in a stationary right angled system of coordinates and connected to said secondary coordinate transformers for converting the integrated components into polar coordinate quantities which control said sighting means, manually controllable tracking means individual to each of said primary coordinate transformers and adjustable to positions which. are calculated fromsaid 'correcting' quantities values that are proportional to the projections of said correcting quantities in said right angled system of coordinates and means for transferring said values to said automatically adjustable devices forproducing said components of speed and supplying them to said speed integrators.

2. A device according to claim 1 and in which there is provided, between said correcting members and said primary coordinate transformers, devices for differentiating the movements of said correcting members and transferring to said primary transformers operating quantities proportional to the time derivatives.

3. A device according to claim 1, in which there is provided, between said correcting members and said primary coordinate transformers, devices for differentiating the movements of said correcting members and transferring to said primary transformers operating quantities proportional to the time derivatives, and in which said differentiating devices consist of tachometer generators.

4. A device according to claim 1 and in which said adjustable devices are devised to integrate values received from said primary coordinate transformers and supply the integratedvalues to said speed integrators for;- further integration.

5. A device according to claim 1, in which said adjustable devices are devised to integrate values received from said primary coordinate transformers and supply the integrated values to said speed integrators for further integration, and in which the correcting quantities consist of voltages, said adjustable devices consisting of electric motors the rotary velocity of which is proportional t the voltage. 1

References Cited in the file of this patent UNITED STATES PATENTS 

